Abstract 9015: Correlation between Spatial Repolarization and Peak-to-end of the T Wave on Transmural Left Ventricular and Body Surface Electrocardiographic Recordings

Abstract

Background. Previous studies showed that Tp-e is a marker of transmural dispersion of ventricular repolarization. Objectives. We studied the relationship between a) the interval between peak and end of the T wave (Tp-e) on local transmural electrograms (transmural Tp-e) or body surface ECG (surface Tp-e) and b) the intracardiac left ventricular (LV) repolarization during QT interval prolongation. Methods. Using a canine anthopleurin-A model, transmural LV electrograms were recorded via needle electrodes placed in the baso-anterior, mid-anterior, apico-anterior, baso-lateral, mid-lateral, and apico-lateral LV wall. Recovery time (RT) was calculated as an index of local repolarization at each transmural unipolar electrode. Results. RT was longer at the LV apex than that at the base, and longer in the lateral than in the anterior wall. A high correlation was found between transmural Tp-e and the transmural RT-dispersion (figure 1). On the other hand, surface Tp-e was correlated with total spatial LV RT-dispersion, though not with transmural RT-dispersion (figure 2). The slope of the linear correlation between surface Tp-e and total spatial LV RT-dispersion was 1.04 (P < 0.001), whereas betwwen surface Tp-e and averaged transmural RT-dispersion was 0.25 (P < 0.001). The shortest RT in the heart corresponded to the peak, whereas the longest RT coincided with the end of the T wave on the surface ECG. Conclusions. Surface Tp-e may overestimate the transmural dispersion of LV repolarization, and seems to express the special distribution of repolarization in the whole LV during iatrogenic QT interval prolongation.